JPH10288137A - Pinion of starting electric motor for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a starting electric motor for an internal combustion engine capable of reducing the number of gear teeth while securing strength of an output shaft and a pinion tooth and realizing reduction of size and weight without spoiling strength. SOLUTION: This pinion is a pinion 7A with gear teeth on its outerperipheral surface and with a bearing 8 fit on its inner peripheral surface, provided on an output shaft 6 of a starting electric motor through the bearing and constituted to start an internal combustion engine as it slides along the output shaft 6 and the gear teeth is engaged with a ring gear of the internal combustion engine. In this case, an inside diameter of a head end part 7a on the side to be engaged with the ring gear is set in the size between an inside diameter and an outside diameter of the bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pinion of a starter motor used for an internal combustion engine of an automobile or the like, and more particularly to a pinion of a starter motor for an internal combustion engine which is small and lightweight.

[0002]

2. Description of the Related Art FIG. 4 is a partial sectional view showing a conventional starting motor for an internal combustion engine referred to, for example, in Japanese Patent Publication No. 7-37785. 5 is an enlarged sectional view showing a pinion portion in FIG. 4, and FIG. 6 is a side view of the pinion portion in FIG. 4 viewed from an axial direction.

In each of the drawings, an electromagnetic switch device 1 is mounted on a motor for starting an internal combustion engine (not shown), and the electromagnetic switch device 1 drives a plunger 2 in an axial direction. The lever 3 interlocked with the plunger 2 has an upper end engaged with the plunger 2 and a lower end engaged with a rear portion (an end surface opposite to an operation surface) of an overrunning clutch device 4 (described later), and is centered on the fulcrum 3a. To rotate.

[0004] The starting motor is a rotating armature 5.
And an output shaft 6 integrally extended with the rotating shaft of the armature 5. A helical spline (not shown) is formed on the outer peripheral portion of the output shaft 6, and the overrunning clutch device 4 meshes with the helical spline of the output shaft 6 so as to be slidable in the axial direction.

[0005] A pinion 7 meshing with a ring gear (not shown) of the internal combustion engine is connected to the overrunning clutch device 4 so as to be rotatable only in one direction (starting direction of the internal combustion engine).

A plurality of gear teeth 7G meshing with the ring gear are provided on the outer peripheral surface of the pinion 7, and a bearing 8 is fitted on the inner peripheral surface. Further, the pinion 7 slides in the axial direction along the output shaft 6.

Next, the operation of the pinion of the conventional starting motor for an internal combustion engine shown in FIGS. 4 to 6 will be described. First, when a key switch (not shown) of the internal combustion engine is closed by a driver's operation, an exciting coil (not shown) in the electromagnetic switch device 1 is energized, and the plunger 2 is moved rearward (left side in FIG. 4). Is sucked.

The lever 3 is moved by the suction movement of the plunger 2.
Rotates the fulcrum 3a and moves the overrunning clutch device 4 forward (to the right in FIG. 1). Thus, the pinion 7 connected to the overrunning clutch device 4 moves forward along the output shaft 6 together with the overrunning clutch device 4, and the gear teeth 7G mesh with the ring gear of the internal combustion engine.

Further, a movable contact (not shown) in the electromagnetic switch device 1 is also moved by the suction movement of the plunger 2,
The movable contact comes into contact with a fixed contact (not shown) located behind.

As a result, the armature 5 is energized and rotates, and the torque is transmitted to the pinion 7 via the output shaft 6, the helical spline and the overrunning clutch device 4, and the gear teeth 7G of the pinion 7 Then, the internal combustion engine is started via the ring gear.

As described above, the internal combustion engine is started via the pinion 7 which meshes with the ring gear. In recent years, the number of accessories around the vehicle engine has increased, and a reduction in fuel consumption has been required. Therefore, it is desired to reduce the size of the starting motor.

In order to reduce the size, it is conceivable to increase the gear ratio between the pinion 7 and the ring gear. As a result, it is possible to reduce the weight of the starting motor by an amount corresponding to the increased gear ratio. it can. Specific methods for increasing the gear ratio include a first method for increasing the number of teeth of the ring gear and a second method for decreasing the number of gear teeth 7G of the pinion 7.

However, in the first method, since the diameters of the engine and the transmission increase as the number of teeth of the ring gear increases, it is necessary to increase the size of the engine room when considering each layout in the engine room of the vehicle. As a result, the weight of the vehicle is increased.

In the second method, as the gear teeth 7G of the pinion 7 decrease, the shaft strength of the output shaft 6 and the pinion 7
As the tooth root strength decreases, the number of teeth is limited,
Weight reduction cannot be sufficiently realized.

In general, the number of teeth of the pinion 7 used in the starting motor is eight when the module is 2.54 (diametral pitch is 10) when the strength is secured. Is 2.117 (diametral pitch is 12), the minimum number is nine.

The module value to be applied is determined according to the specification of the ring gear. FIG. 6 shows a pinion 7 having nine teeth with a module 2.117 (diametral pitch 12). ing.

Therefore, if the number of teeth of the pinion 7 is set smaller than the minimum number of teeth, it is necessary to at least make the output shaft 6 thin or reduce the thickness of the bottom of the pinion 7. , The pinion 7 or the output shaft 6 may be damaged.

[0018]

As described above, in the conventional pinion of the starting motor for an internal combustion engine, since the inner diameter of the pinion 7 is formed constant in the axial direction, the weight can be reduced without impairing the strength. There was a problem that can not be.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to reduce the number of gear teeth while securing the strength of the output shaft and the pinion tooth bottom, thereby reducing the size and weight without reducing the strength. It is an object of the present invention to obtain a pinion of a starting motor for an internal combustion engine, which realizes the realization.

[0020]

A pinion of a starting motor for an internal combustion engine according to the present invention is a pinion having gear teeth on an outer peripheral surface and a bearing fitted on an inner peripheral surface. The pinion of the starting motor for the internal combustion engine, which is provided on the output shaft of the starting motor, slides along the output shaft and engages the gear teeth with the ring gear of the internal combustion engine to start the internal combustion engine. The inner diameter of the tip is set to a value between the inner diameter and the outer diameter of the bearing.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 is a partial sectional view showing Embodiment 1 of the present invention, FIG. 2 is an enlarged sectional view showing a pinion portion in FIG. 1, and FIG. 3 is a view of the pinion portion in FIG. It is a side view.

In each figure, the same components as those described above are denoted by the same reference numerals, and the detailed description thereof will be omitted. The basic operation of the starting motor is the same as described above, and will not be described in detail here.

In this case, the inner peripheral surface of the tip portion 7a of the pinion 7A is connected to the output shaft 6
The pinion 7A has an inner diameter at the front end portion 7a smaller than the inner diameter at the center portion 7b and the rear end portion 7c.

That is, the inner diameter of the tip 7a is formed between the inner diameter and the outer diameter of the bearing 8, thereby ensuring the root strength of the pinion 7A.

The inner diameter of the central portion 7b of the pinion 7A is set to be equal to the outer diameter of the bearing 8, and the rear end portion 7c of the pinion 7A is formed in a brim shape to secure a strength. ing.

As shown in FIG. 1 and FIG. 2, by forming the tip 7a of the pinion 7A into a drawing shape, a module 2.117 (diametral pitch 1) similar to that described above (FIG. 6) is obtained.
Even when 2) is applied, as shown in FIG. 3, the number of gear teeth 7G can be reduced to eight. As a result, as shown in FIG. 1, the outer diameter and the root diameter of the pinion 7A are necessarily reduced.

Although the outer diameter of the output shaft 6 is formed small in order to secure the bottom thickness of the gear teeth 7G of the pinion 7A, in order to avoid a significant decrease in the strength of the output shaft 6,
The outer diameter of the output shaft 6 cannot be made too small. Therefore, as shown in FIG. 1, the root thickness at the central portion 7b of the pinion 7A is formed thinner than the conventional example (see FIG. 4).

When the pinion 7A shown in FIG. 1 is pushed forward by the lever 3, and the gear teeth 7G mesh with the ring gear of the internal combustion engine, the load and impact force acting on the pinion 7A are the largest at the pinion tip 7a. Become.

Normally, since the pinion 7A is formed by cold forging and the rear end 7c has a brim shape, it is understood that the strength of the pinion 7A is weakest at the front end 7a.

Therefore, by forming the drawing shape as described above and securing the thickness of the tip portion 7a having the weakest strength, the pinion 7A having a small number of teeth without any problem in strength.
Can be realized.

In the first embodiment, the case where the number of gear teeth 7G is reduced to eight has been described by taking the case where the module is 2.117 (diametral pitch is 12) as an example. In the case of 54 (diametral pitch is 10), it is needless to say that the number can be reduced to seven.

[0032]

As described above, according to the present invention, a pinion having gear teeth on the outer peripheral surface and having a bearing fitted on the inner peripheral surface is provided on the output shaft of the starting motor via the bearing. In the pinion of a starter motor for an internal combustion engine that starts the internal combustion engine by sliding along the output shaft and the gear teeth mesh with the ring gear of the internal combustion engine, the inner diameter of the tip end on the side that meshes with the ring gear is defined as a bearing. Because the size is set between the inner and outer diameters of the internal combustion engine, the number of gear teeth can be reduced while ensuring the strength of the output shaft and the pinion tooth bottom, and a compact and lightweight internal combustion engine without losing strength There is an effect that an engine starting motor can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a starting motor to which Embodiment 1 of the present invention is applied.

FIG. 2 is an enlarged sectional view showing a pinion portion in FIG. 1;

FIG. 3 is a side view of the pinion portion in FIG. 1 viewed from the axial direction.

FIG. 4 is a partial sectional view showing a pinion of a conventional starting motor.

FIG. 5 is an enlarged sectional view showing a pinion portion in FIG. 4;

FIG. 6 is a side view of the pinion portion in FIG. 4 as viewed from the axial direction.

[Explanation of symbols]

6 output shaft, 7A pinion, 7a tip, 7b center, 7G gear teeth, 8 bearings.

Claims (1)

[Claims] 1. A pinion having gear teeth on an outer peripheral surface and bearings fitted on an inner peripheral surface, the pinion is provided on an output shaft of a starting motor via the bearings, and slides along the output shaft. In the pinion of a starter motor for an internal combustion engine that starts the internal combustion engine by moving the gear teeth and meshing with a ring gear of the internal combustion engine, an inner diameter of a tip end on a side that meshes with the ring gear is defined as an inner diameter of the bearing. A pinion of a starting motor for an internal combustion engine, wherein the pinion is set to a size between the diameter and the diameter.